Hundreds of worshipers and more than 60 Roman Catholic bishops celebrated a Mass yesterday to mark the 40th anniversary of Washington's National Shrine of the Immaculate Conception and to dedicate a 37-ton sculpture planned as the last major addition to the basilica.

During the ceremony, people peeked over their shoulders to gaze at the 780-square-foot marble relief, which covers the south wall of the basilica's Upper Church.

The sculpture, "Universal Call to Holiness," portrays people of various ages and races gathered around a dove that symbolizes the Holy Spirit. Much plainer than the glittering mosaics and huge pillars that adorn other areas of the basilica, the sculpture was designed to reflect the diversity of Catholicism and the belief that every person is a unique creation of God, said Susan Gibbs, spokeswoman for the Archdiocese of Washington.

"No one is excluded," Cardinal James Hickey, archbishop of Washington, said as he blessed the sculpture. "Everyone is called to holiness. . . . What earthly artisans have portrayed in stone, the Holy Spirit, Divine Artisan, is bringing to life in our hearts."

Hickey recommended the sculpture's theme, an interpretation of a Roman Catholic document, Lumen Gentium, that urges followers to "live as is fitting among saints" and to display everyday compassion, kindness and patience.

The sculpture was designed by Maryland artist George S. Carr and crafted by 22 Italian marble workers. Joseph and Bertha Braddock, of Alexandria, paid for the five-year project with a $1 million donation from their Aztec Foundation charity.

The Braddock family walked with the bishops during a procession as clergymen sprinkled holy water on people in the pews. After the two-hour Mass, many paused to look at the sculpture, engraved with images that include the Virgin Mary, Pope John Paul II and Mother Teresa.

The Byzantine style of the National Shrine makes it easy to incorporate new works, Gibbs said. "As each new wave of immigrants comes in, we build a new chapel," she said. The church "is really a reflection of the U.S. and its changing cultures."

When the basilica opened, the entire structure was brick and mortar, with only a large mosaic of Christ to decorate the altar. In the decades that followed, 65 chapels, smooth marble walls and ornate stained-glass windows were added, said Peter Sonski, a spokesman for the shrine. With the sculpture in place, the last of the major church projects is complete.

Many attendees mingled on the steps of the church after the Mass, taking pictures and chatting about the artwork.

"It's gorgeous," said Darlene Cottrell, a Michigan resident visiting Washington. "It combines all religions together and shows all people together working for peace."

For 40 years, 87-year-old Washington resident Jeannette Miller has watched the basilica evolve from an empty parcel of land in Northeast Washington's Brookland neighborhood to the world's eighth-largest church.

During yesterday's Mass, Miller whispered to her son to take photos of her favorite moments: the majestic parade of bishops, the dedication ceremony, row after row of fellow Catholics breathing in the scent of incense and exclaiming over the new sculpture.

The church has played a special part in her life, she said. During several years in the Foreign Service, Miller said, the basilica was a cherished memory of home.

"It always gave me something to hold on to," said Miller, as she left the church after receiving Communion. "I never thought that I would ever see this completed."

CAPTION: The new marble sculpture "Universal Call to Holiness" rises behind worshipers at the shrine's 40th anniversary Mass.

CAPTION: Cardinal James Hickey, archbishop of Washington, blesses the sculpture with a palm branch and holy water. More than 60 bishops attended the Mass.